The item is a flight safety critical aircraft part (fscap).
A nut having 6 flat sides and an integral washer which extends beyond the flats or periphery. An integral feature is incorporated for locking on the threads of a mating member.
Classification: Nuts of iron or steel
NSN 6610-01-391-5092
NSN 6650-01-411-3904
NSN 5910-00-817-5803
NSN 6610-01-545-5648
NSN 6110-01-415-5086
NSN 5999-00-200-9722
NSN 5975-00-300-0731
NSN 5965-01-519-1214
NSN 6145-01-501-3489
NSN 5960-01-531-9108
NSN 5935-01-158-4793
NSN 5925-01-579-6730